* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
* \brief Provides timers which are event sources in the task system.
* Three types of timers are supported:
*\li 'ticker' timers generate a periodic tick event.
*\li 'once' timers generate an idle timeout event if they are idle for too
* long, and generate a life timeout event if their lifetime expires.
* They are used to implement both (possibly expiring) idle timers and
*\li 'limited' timers generate a periodic tick event until they reach
* their lifetime when they generate a life timeout event.
*\li 'inactive' timers generate no events.
* Timers can change type. It is typical to create a timer as
* an 'inactive' timer and then change it into a 'ticker' or
* The module ensures appropriate synchronization of data structures it
* creates and manipulates.
* Clients of this module must not be holding a timer's task's lock when
* making a call that affects that timer. Failure to follow this rule
* can result in deadlock.
* The caller must ensure that isc_timermgr_destroy() is called only
* once for a given manager.
#include <isc/eventclass.h>
isc_timertype_undefined = -1, /*%< Undefined */
isc_timertype_ticker = 0, /*%< Ticker */
isc_timertype_once = 1, /*%< Once */
isc_timertype_limited = 2, /*%< Limited */
isc_timertype_inactive = 3 /*%< Inactive */
typedef struct isc_timerevent {
#define ISC_TIMEREVENT_FIRSTEVENT (ISC_EVENTCLASS_TIMER + 0)
#define ISC_TIMEREVENT_TICK (ISC_EVENTCLASS_TIMER + 1)
#define ISC_TIMEREVENT_IDLE (ISC_EVENTCLASS_TIMER + 2)
#define ISC_TIMEREVENT_LIFE (ISC_EVENTCLASS_TIMER + 3)
#define ISC_TIMEREVENT_LASTEVENT (ISC_EVENTCLASS_TIMER + 65535)
/*% Timer and timer manager methods */
void (*destroy)(isc_timermgr_t **managerp);
isc_result_t (*timercreate)(isc_timermgr_t *manager,
const isc_time_t *expires,
const isc_interval_t *interval,
void (*attach)(isc_timer_t *timer, isc_timer_t **timerp);
void (*detach)(isc_timer_t **timerp);
isc_result_t (*reset)(isc_timer_t *timer, isc_timertype_t type,
const isc_time_t *expires,
const isc_interval_t *interval,
isc_result_t (*touch)(isc_timer_t *timer);
* This structure is actually just the common prefix of a timer manager
* object implementation's version of an isc_timermgr_t.
* Direct use of this structure by clients is forbidden. timer implementations
* may change the structure. 'magic' must be ISCAPI_TIMERMGR_MAGIC for any
* of the isc_timer_ routines to work. timer implementations must maintain
isc_timermgrmethods_t *methods;
#define ISCAPI_TIMERMGR_MAGIC ISC_MAGIC('A','t','m','g')
#define ISCAPI_TIMERMGR_VALID(m) ((m) != NULL && \
(m)->magic == ISCAPI_TIMERMGR_MAGIC)
* This is the common prefix of a timer object. The same note as
* that for the timermgr structure applies.
isc_timermethods_t *methods;
#define ISCAPI_TIMER_MAGIC ISC_MAGIC('A','t','m','r')
#define ISCAPI_TIMER_VALID(s) ((s) != NULL && \
(s)->magic == ISCAPI_TIMER_MAGIC)
*** Timer and Timer Manager Functions
*** Note: all Ensures conditions apply only if the result is success for
*** those functions which return an isc_result_t.
isc_timer_create(isc_timermgr_t *manager,
const isc_time_t *expires,
const isc_interval_t *interval,
* Create a new 'type' timer managed by 'manager'. The timers parameters
* are specified by 'expires' and 'interval'. Events will be posted to
* 'task' and when dispatched 'action' will be called with 'arg' as the
* arg value. The new timer is returned in 'timerp'.
*\li For ticker timers, the timer will generate a 'tick' event every
* 'interval' seconds. The value of 'expires' is ignored.
*\li For once timers, 'expires' specifies the time when a life timeout
* event should be generated. If 'expires' is 0 (the epoch), then no life
* timeout will be generated. 'interval' specifies how long the timer
* can be idle before it generates an idle timeout. If 0, then no
* idle timeout will be generated.
*\li If 'expires' is NULL, the epoch will be used.
* If 'interval' is NULL, the zero interval will be used.
*\li 'manager' is a valid manager
*\li 'task' is a valid task
*\li 'action' is a valid action
*\li 'expires' points to a valid time, or is NULL.
*\li 'interval' points to a valid interval, or is NULL.
*\li type == isc_timertype_inactive ||
* ('expires' and 'interval' are not both 0)
*\li 'timerp' is a valid pointer, and *timerp == NULL
*\li '*timerp' is attached to the newly created timer
*\li The timer is attached to the task
*\li An idle timeout will not be generated until at least Now + the
* timer's interval if 'timer' is a once timer with a non-zero
isc_timer_reset(isc_timer_t *timer,
const isc_time_t *expires,
const isc_interval_t *interval,
* Change the timer's type, expires, and interval values to the given
* values. If 'purge' is TRUE, any pending events from this timer
* are purged from its task's event queue.
*\li If 'expires' is NULL, the epoch will be used.
*\li If 'interval' is NULL, the zero interval will be used.
*\li 'timer' is a valid timer
*\li The same requirements that isc_timer_create() imposes on 'type',
* 'expires' and 'interval' apply.
*\li An idle timeout will not be generated until at least Now + the
* timer's interval if 'timer' is a once timer with a non-zero
isc_timer_touch(isc_timer_t *timer);
* Set the last-touched time of 'timer' to the current time.
*\li 'timer' is a valid once timer.
*\li An idle timeout will not be generated until at least Now + the
* timer's interval if 'timer' is a once timer with a non-zero
isc_timer_attach(isc_timer_t *timer, isc_timer_t **timerp);
* Attach *timerp to timer.
*\li 'timer' is a valid timer.
*\li 'timerp' points to a NULL timer.
*\li *timerp is attached to timer.
isc_timer_detach(isc_timer_t **timerp);
* Detach *timerp from its timer.
*\li 'timerp' points to a valid timer.
*\li If '*timerp' is the last reference to the timer,
* The timer will be shutdown
* The timer will detach from its task
* All resources used by the timer have been freed
* Any events already posted by the timer will be purged.
* Therefore, if isc_timer_detach() is called in the context
* of the timer's task, it is guaranteed that no more
* timer event callbacks will run after the call.
isc_timer_gettype(isc_timer_t *timer);
*\li 'timer' to be a valid timer.
isc_timermgr_createinctx(isc_mem_t *mctx, isc_appctx_t *actx,
isc_timermgr_t **managerp);
isc_timermgr_create(isc_mem_t *mctx, isc_timermgr_t **managerp);
* Create a timer manager. isc_timermgr_createinctx() also associates
* the new manager with the specified application context.
*\li All memory will be allocated in memory context 'mctx'.
*\li 'mctx' is a valid memory context.
*\li 'managerp' points to a NULL isc_timermgr_t.
*\li 'actx' is a valid application context (for createinctx()).
*\li '*managerp' is a valid isc_timermgr_t.
isc_timermgr_destroy(isc_timermgr_t **managerp);
* Destroy a timer manager.
*\li This routine blocks until there are no timers left in the manager,
* so if the caller holds any timer references using the manager, it
* must detach them before calling isc_timermgr_destroy() or it will
*\li '*managerp' is a valid isc_timermgr_t.
*\li All resources used by the manager have been freed.
void isc_timermgr_poke(isc_timermgr_t *m);
* See isc_timermgr_create() above.
(*isc_timermgrcreatefunc_t)(isc_mem_t *mctx, isc_timermgr_t **managerp);
isc__timer_register(void);
* Register a new timer management implementation and add it to the list of
* supported implementations. This function must be called when a different
* event library is used than the one contained in the ISC library.
isc_timer_register(isc_timermgrcreatefunc_t createfunc);
* A short cut function that specifies the timer management module in the ISC
* library for isc_timer_register(). An application that uses the ISC library
* usually do not have to care about this function: it would call
* isc_lib_register(), which internally calls this function.